Directions:

Adjust oven rack to the center position and preheat the oven to 350 degrees F. Line muffin pans with bake-cup liners.

Pour milk, egg whites and vanilla into a medium bowl and mix with a fork until blended.

Mix the flour, sugar, baking powder and salt in the bowl of an electric mixer at the lowest speed. Add the butter pieces; continue beating at low speed until the mixture resembles moist crumbs, with no powdery ingredients remaining, about 1 minute.

Add all but 1/2 cup of the milk mixture to the crumbs and beat at medium speed for 1 minute. Add the remaining 1/2 cup of the milk mixture and beat 30 seconds longer. Stop the mixer and scrape the sides of the bowl. Return the mixer to medium speed and beat about 20 seconds longer.

Pour the batter into muffin cups so that the cups are about 80 percent full. Bake the cupcakes for 15 to 17 minutes. Insert a toothpick in the center of a cupcake. If it comes out clean, it is done.

Transfer the muffin pans to wire cooling racks or away from the hot oven. Let them cool for 10 minutes. Remove cupcakes from the pan and place on racks or plates to continue cooling. Be sure to cool cupcakes completely before frosting, about 1 hour.